The present invention relates generally to memory cards and, more particularly, to a memory card (e.g., a multi-media card (MMC)) comprising a leadframe which, in its original state, is provided with multiple downsets and multiple dambars which allow the tie bars of the leadframe to exit the body of the memory card at or near the center thereof, thus providing a more robust memory card that is less sensitive to “chip-out”.
As is well known in the electronics industry, memory cards are being used in increasing numbers to provide memory storage and other electronic functions for devices such as digital cameras, MP3 players, cellular phones, and personal digital assistants. In this regard, memory cards are provided in various formats, including multi-media cards and secure digital cards.
Typically, memory cards comprise multiple integrated circuit devices or semiconductor dies. The dies are interconnected using a circuit board substrate which adds to the weight, thickness, stiffness and complexity of the card. Memory cards also include electrical contacts for providing an external interface to an insertion point or socket. These electrical contacts are typically disposed on the back side of the circuit board substrate, with the electrical connection to the dies being provided by vias which extend through the circuit board substrate.
In an effort to simplify the process steps needed to fabricate the memory card, there has been developed by Applicant a memory card wherein a leadframe assembly is used as an alternative to the circuit board substrate, as described in Applicant's co-pending U.S. application Ser. No. 09/956,190 entitled LEAD-FRAME METHOD AND ASSEMBLY FOR INTERCONNECTING CIRCUITS WITHIN A CIRCUIT MODULE filed Sep. 19, 2001, the disclosure of which is incorporated herein by reference. As is described in Ser. No. 09/956,190, the leadframe and semiconductor die of the memory card are covered with an encapsulant which hardens into a cover or body of the memory card. The body is sized and configured to meet or achieve a “form factor” for the memory card. In the completed memory card, the contacts of the leadframe are exposed within a common surface of the body, with a die pad of the leadframe and the semiconductor die mounted thereto being disposed within or covered by the body.
Applicant has previously determined that the molding or encapsulation process used to form the body of the card sometimes gives rise to structural deficiencies or problems within the resultant memory card. These problems include portions of the die pad of the leadframe being exposed in the body of the memory card, flash being disposed on the contacts of the leadframe, chipping in a peripheral flange area of the body, and mold gate pull-out wherein a portion of the mold or encapsulating compound is pulled out from within the body, leaving a small recess or void therein. To address these particular problems, Applicant has previously developed a memory card having a “die down” configuration attributable to the structural attributes of the leadframe included therein, and an associated molding methodology employed in the fabrication of such memory card. This die-down memory card is disclosed in Applicant's co-pending U.S. application Ser. No. 10/266,329 entitled DIE DOWN MULTI-MEDIA CARD AND METHOD OF MAKING SAME filed Oct. 8, 2002, the disclosure of which is also incorporated herein by reference.
Applicant has also determined that the molding or encapsulation process used to form the body of the memory card sometimes results in portions of one or more of the tie bars of the leadframe being exposed in the body of the memory card. Such exposure sometimes occurs as a result of the deflashing process used to clean the contacts of the leadframe subsequent to the completion of the molding or encapsulation process used to form the body of the memory card. When one or more of the tie bars of the leadframe is/are exposed in the body of the memory card, the cutting or singulation of the tie bars as occurs to complete the fabrication of the memory card often results in occurrences of “chip-out” in the body at the location wherein the tie bar(s) exits the same. The present invention addresses this particular problem by providing a leadframe which includes multiple downsets and dambars, thus allowing the tie bars to exit the memory card body at or near its center. The two separate dambars of the leadframe (an inner dambar and an outer dambar) are each downset to a different elevation, with the elevation being designed so that the tie bars exit the body of the memory card near the center thereof, thus providing a more robust memory card that is less sensitive to chip-out. These and other attributes of the present invention will be described in more detail below.